Suppose you have a data set that includes the values 20, 30, and 50. If u add a fourth value to this data set, and after doing that the mean if the data is 50, what was the value that you added?
A. -20
B. 40
C. 50
D. 100

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)